A heuristic for placement of limited range wavelength converters in all-optical networks

Abstract

Wavelength routed optical networks have emerged as a technology that can eectively utilize the enormous bandwidth of the optical ®ber. Wavelength converters play an important role in enhancing the ®ber utilization and reducing the overall call blocking probability of the network. As the distortion of the optical signal increases with the increase in the range of wavelength conversion in optical wavelength converters, limited range wavelength conversion assumes importance. Placement of wavelength converters is a NP complete problem [K.C. Lee, V.O.K. Li, IEEE J. Lightwave Technol. 11 (1993) 962±970] in an arbitrary mesh network. In this paper, we investigate heuristics for placing limited range wavelength converters in arbitrary mesh wavelength routed optical networks. The objective is to achieve near optimal placement of limited range wavelength converters resulting in reduced blocking probabilities and low distortion of the optical signal. The proposed heuristic is to place limited range wavelength converters at the most congested nodes, nodes which lie on the long lightpaths and nodes where conversion of optical signals is signi®cantly high. We observe that limited range converters at few nodes can provide almost the entire improvement in the blocking probability as the full range wavelength converters placed at all the nodes. Congestion control in the network is brought about by dynamically adjusting the weights of the channels in the link thereby balancing the load and reducing the average delay of the trac in the entire network. Simulations have been carried out on a 12-node ring network, 14-node NSFNET, 19-node European Optical Network (EON), 28-node US long haul network, hypothetical 30-node INET network and the results agree with the analysis. Ó

Impact of node switching capabilities on the performance of wavelength routed networks

“…When adopting sparse selection or conversion, the placement of these capabilities must be optimised. The optimal placement has been proven to be NPcomplete [12,18,19]; heuristic algorithms have also been proposed [20,21] to solve this problem. In our simulations, we used the following heuristic (from Reference [20]) for the assignment of both sparse selection and sparse conversion capabilities: we start from a scenario where the capability is present in all the nodes and we rank them z Differently from Reference [5], where networks with fixed transmitters and receivers and absence of wavelength conversion are not studied because full connectivity is not guaranteed, we consider this case (adding the condition that the two transponders work on the same wavelength), because this scenario is typical of many present optical networks.…”

Converter placement in wavelength routing mesh topologies

“…The performance of the heuristics are kvaluated on two network topologies: the NSFNET (181 and the European Optical Network (EON) [15]. We consider one traffic pattern each for the NSFNET and for the EON.…”

“…We consider two objective functions in our study: the average blocking probability and the maximum blocking probability over all paths. Some heuristics have been proposed recently for placing converters to minimize average blocking probability in mesh topologies [14], [15], [16]. In [14] and [IS], a heuristic that places the converters one by one sequentially is proposed, while a heuristic for the placement of limited range wavelength converters is presented in [15].…”

“…Some heuristics have been proposed recently for placing converters to minimize average blocking probability in mesh topologies [14], [15], [16]. In [14] and [IS], a heuristic that places the converters one by one sequentially is proposed, while a heuristic for the placement of limited range wavelength converters is presented in [15]. In this paper, we propose a class of heuristic algorithms for the converter placement problem, and evaluate the performance of some algorithms in that class.…”

On the management of wavelength converter allocation in WDM all-optical networks

“…[6] and [3] mainly focus on the type b wavelength converter placement problem. In terms of type a and c wavelength converter placement problems, the benefits of using wavelength converters in wavelength routed all-optical networks have been studied in [7]- [11] under various assumptions. Usually, the analytical models are derived from simple topologies and algorithms are proposed under statistical independence assumptions.…”